Abstract [en]

Trensums Food AB is a company that produces a wide variety of food products to different global trademark owners. Some of the products produced by Trensums Food AB are different kind of sauces, including BBQ-sauce and vanilla sauce. The sauce products are considered safe when an acid is added resulting in a pH < 4,2. The outsource of the company claims that it is important to use acetic acid instead of other kind of acids and that the pH is not crucial to consider the product safe. The goal of this project was to investigate how effectively different kind of organic acids work against microorganisms in the BBQ-sauce and milk-based sauce produced by Trensums Food AB. The main antimicrobial activity of an acid depends on its concentration of undissociated acid. Which further depends on the pKa-value of the acid and also the surrounding pH in the product. The pH was measured in the products to see if pH is critical for the antimicrobial activity or if the choice of acid is more important. The acids used in this project was acetic acid, citric acid and lactic acid and they were tested on Candida utilis, Bacillus subtilis and Enterococci faecium. BBQ-sauce and milk-based sauce were made in different batches containing 0, 0,12, 0,24 and 0,36 weight percent of respective acid. Each batch contained 103 CFU/ml of respective microorganism. After 5 days of incubation a viable count was performed. The acetic acid was the most effective acid in both type of sauces, reducing all microorganisms below the detection limit (< 101 CFU/ml) in the BBQ-sauce within all batches. The citric acid and lactic acid reduced only E.faecium and B.subtilis to a value below the lowest level of detection. In the milk-based sauce, which was contaminated with additional microorganisms, it was only the acetic acid that showed an increasing effect of antimicrobial activity with increasing concentration of acid. The pH was lower in the BBQ-sauce when using citric acid and lactic acid compared to when using acetic acid. Thus concluding that the antimicrobial activity of the selected microorganisms is not solely dependent on the level of pH but additionally the type of acid being used. The acetic acid has a higher pKa-value compared to the other acids and is therefore to a higher extent in a undissociated state.